Question

An atom of gold has a mass of 3.271 x 10-22g. How many atoms of gold are in 5.00g of gold?

Answer 1

To get the number of gold atoms, you have to divide the mass of the gold by the mass of the gold atom. It follows this simple equation  $\frac{mass of gold}{mass of gold atom}$. 

Let x be the number of gold atoms. Plug in the values to a calculator.

x = $\frac{5.00g}{3.271 x 10-22g}$
Both have the same units so the unit gram(g) can be cancelled. 
x then would be equal to 1.53x10^22. So there are 1.53x10^22 atoms of gold in 5 g of gold